If you are serious about not losing your images, I'd suggest:
1. External drive for parallel storage in a mobile package
2. Back-ups on DVDs stored on a different location
This should give you some protection against both disk-crashes on your computer and against fire/water and other on-site damage...
I'm not sure if you can get archival-quality DVDs, but there are archival-quality CDs...buut that may be too much effort against what is hopefully a very remote chance of everything breaking at the same time. 5 years from now there will be some sort of common Blue-Ray+ format that everyone has gone to anyway...